Apparatus for bending the edge of a foil around the edge of a tray

ABSTRACT

An apparatus for sealing trays with an aluminium foil, having a carrier plate for the tray which can be lifted and lowered with the tray and folding tools for bending that portion of the aluminium foil extending beyond the edges of the trays under the bent edge of the tray. The folding tools comprise slides which can be moved against the tray from the outside and which are mounted or designed, and operate conjointly with closing brackets or other actuation means, in such a manner that, during the bending operation, the edges of the aluminium foil are first pressed against the tray from the outside and, during the final phase, are pressed into the hollow behind the edge of the tray from below. This ensures an especially secure, tight closure between foil and tray in one step.

United States Patent 1 Schierle 51 May 13,1975

[ APPARATUS FOR BENDING THE EDGE OF A FOIL AROUND THE EDGE OF A TRAY[76] Inventor: Eugen Schierle, in den Ringelgarten 58, D-7000 Stuttgart,Germany [22] Filed: Oct. 19, 1973 [211 Appl. No.: 408,111

[30] Foreign Application Priority Data Oct. 27, 1972 Germany 2252927[52] US. Cl. 53/354 [51] Int. C1. B65B 7/28; B67B 3/14 [58] Field ofSearch 53/329, 344, 345, 346, 53/342, 350, 378, 371, 364, 365, 290, 296,297, 354

[56] References Cited UNITED STATES PATENTS 2,704,628 3/1955 Stanton,Jr. et al. 53/344 3,036,416 5/1962 Cheeley et al. 53/354 X 3,224,16312/1965 Ray 53/329 3,253,380 5/1966 Cheeley et al. 53/345 X 3,261,1447/1966 Weber 53/344 Primary Examiner-Travis S. McGehee AssistantE.\'aminerHorace M. Culver Attorney, Agent, or FirmCraig & Antonelli[57] ABSTRACT An apparatus for sealing trays with an aluminium foil,having a carrier plate for the tray which can be lifted and lowered withthe tray and folding tools for bending that portion of the aluminiumfoil extending beyond the edges of the trays under the bent edge of thetray. The folding tools comprise slides which can be moved against thetray from the outside and which are mounted or designed, and operateconjointly with closing brackets or other actuation means, in such amanner that, during the bending operation, the edges of the aluminiumfoil are first pressed against the tray from the outside and, during thefinal phase, are pressed into the hollow behind the edge of the trayfrom below. This ensures an especially secure, tight closure betweenfoil and tray in one step.

11 Claims, 4 Drawing Figures PATE T HAY 1 3197's SHEET 10F 2 APPARATUSFOR BENDING THE EDGE OF A FOIL AROUND THE EDGE OF A TRAY The presentinvention relates to an apparatus for bending the edge of a foil ofaluminium or a similar material around the edge of a tray, having acentering basket and a stop plate, which hold the tray and the foilbetween them and which can be advanced one toward the other, and furtherhaving slides which contact the edge of the foil from the outside as itbends during the advancing movement.

In a known apparatus of this type (US. Pat. No. 3,036,416), the tray andthe lid foil are advanced against a stop plate, which is then takenalong and placed against a sealing apparatus. This sealing apparatus hasdownwardly protruding edges, which bend the lid foil toward the tray.The bent edges of the lid foil are then pressed against the tray bymeans of slides which can be advanced toward the tray. A separate drive,taken from a cam disc, is provided for the slides, with the drive movingthe slides diagonally to the tray, whose surface is generallyrectangular. With the aid of this apparatus, the edges of the lid foilare only bent around the edges of the tray, without mutual tensioning.The danger exists that sufficient tightness cannot be achieved in thismanner, as at least a drip-proof closure must be ensured if containerssealed in this manner are to be employed for the storage of foods orsimilar items.

The object of the invention is to create an apparatus of the typeindicated at the outset which ensures a dripproof sealing of the tray bymeans of the lid foil. According to the invention the centering baskethas a closing bracket which is movable in the direction of advance andwhich contacts the slides, which are movable in the direction ofadvance, in the final position of the centering basket and the stopplate. This presses the slides against the stop plate to complete thesealing operation and tension the edge of the lid foil and the tray withone another to form a tight sea].

In a development of the invention, the slides are pivotally arrangedabout shafts which extend parallel to the edges of the tray. Thispivotal arrangement of the slides, whose swivel shaft is located abovethe stop plate, has a favourable effect on the operation of bending theedges of the lid foil against the side walls of the tray, as the edgesare pressed from the top to the bottom.

In an additional advantageous development of the invention, there arelevers between a base plate and the stop plate, which is in a movablesupporting relationship with the base plate against the effect of one ormore springs, with the levers supporting the slides by means of rod-likeattachments located laterally next to the stop plate. This arrangementand design of the slides ensures that the normal advance movement whenthe tray and the lid are loaded is transmitted into a swivel movement tobe performed by the slides, without requiring further drive means.

In an additional advantageous development of the invention, only thosesections of the slides located in the straight-line area of the edges ofthe tray, which has rounded corners in a known manner, are movable inthe direction of advance, thereby avoiding additional pressing of thetwo edges in the area of the corners. Actual practice has shown that thepleating of the lid foil occurring in the area of the corners providessufficient tightness, without axial pressing being required. Thisprovides the additional advantage that the corners of the lid foil canbe extended downward and utilized as pull tabs for opening the tray. Ina practical embodiment of the invention, the movable sections of theslides are retained on the rodlike attachments with springs.

In order to prevent the edge of the tray, which usually has an annularbead, from being destroyed during sealing, it is advantageous if theplate-shaped slides have a stem which engages behind an annular bead ofthe edge of the tray, thereby limiting pressing between the edges of thelid foil and the tray to a certain area.

It is structurally advantageous if the corner sections of the slides,which contact the corner sections of the neighbouring slides in theclosed position, are set back relative to the straight moving sections,thereby making the closure of the corners less intensive, which howeveris not disadvantageous for the above mentioned reason. This designpermits the advantage that, in a further development of the invention,the corners of the centering basket have extensions which extend rightto the edge of the tray. This permits forces of relatively largemagnitude to be transmitted to the stop plate from the centering basketwithout crushing the tray.

In order to avoid having to also provide separate drive means for thecentering basket and the closing bracket, in a further development ofthe invention the centering basket is kept in a supporting relationshipwith the closing bracket by means of one or more springs which arestronger than the springs which retain the stop plate. This ensures thatthe closing bracket is not moved until the centering basket and the stopplate have moved to their final position.

In order to bend the edge of the lid foil as the tray and the lid foilwhich are held in the centering basket are pressed against the stopplate, it is advantageous if the stop plate has a recess correspondingto the size of the lid to be created.

The above discussed and other objects, features and advantages of thepresent invention will become more apparent from the followingdescription thereof, when taken in connection with the accompanyingdrawings, in which FIGS. 1a and lb show a vertical section through anembodiment according to the invention in the initial position and in theclosed position; and

FIGS. 2a and 2b show a top view of lateral slides in the initialposition and in the closed position.

With the apparatus according to the invention, trays 1, which arepreferably of aluminium foil or a similar metallic foil, are to besealed automatically with a foil 2, which is also an aluminium foil oranother metallic foil. Tray 1 and foil 2 are represented by dash-dottedlines. Tray 1 has an outwardly projecting edge, which has an annularbead 3 on the outside. Foil 2 is bent around annular bead 3 of thisedge, whereby a dripproof closure should be achieved, as trays of thistype are employed especially for the storage of prepared foods.

Filled tray 1 is placed in a centering basket 4 automatically by meansof an unillustrated apparatus; the inclination of the side walls ofcentering basket 4 correspond to the inclination of the side walls oftray 1. The corners of centering basket 4 have extensions 5, which arein a contacting relationship with the edge of tray 1 "mm the bottom.Foil 2 is also placed on tray I auto: rnatically in an unillustratedmanner.

The centering basket is lifted by means of a piston 6,

and advanced against a stop plate 7. The bottom of stop plate 7 has arecess S corresponding generally with the lid to be produced, so thatthe edge of foil 2 is bent :lownward around annular bead 3 whencentering basket 4, containing tray 1, is pressed against stop plate 7.

Stop plate 7 is slidably arranged in a base plate 11 by means of apiston 9 against the effect of a spring 10,.

and its movement is limited by means of a stop 12 surroundingpiston 9.When tray 1 and foil 2 are pressed against stop plate 7 by centeringbasket 4, stop plate 7 can yield a given distance until it contacts itsstop 12. This movement is transmitted to slides 14 in a lateral movementby means of levers 13 arranged between base plate 11 and stop plate 7.Levers 13, which must be inclined relative to the direction of advanceof centering basket 4, are mounted between stop plate 7 and base plate11 in bearing blocks 15 and 16, with a slot guide being provided inbearing blocks 16 of base plate 11. Swivel shaft 17 of bearing blocks 15extends vertically above the edges of tray 1 and parallel thereto.

Rod-like attachments 18 protrude downward from le- Slides 14 are movablyattached to rod-like attach-.

ments 18 in the direction of the advance of centering basket 4 and thesliding movement of stop plate 7, and

. like attachments 18. In addition, section 26 is'set back relative tosection with respect to the side walls of tray 1. Furthermore, onlysection 25 has a stemf21..,

are retained in the initial position shown in FIG. 1a by means ofsprings 19. As a result of this movable attach-. ment, slides 14 can bemoved upward by means of a closing bracket 20 when centering basket 4and stop plate 7 have reachedtheir end positions. As can be seen fromFIG. 1b, this swivels slides 14 upward above rod-like attachments 18.They engage behind bead 3 of the edge of tray 1 with a stem 21, andpress the edge of foil 2, which is bent around bead 3, upward, thusproducing a secure connection which is at least dripproof. I

In order to avoid having to provide separate drive means for closingbracket 20, centering basket 4 is movably supported against piston 6 bymeans of bolts 22 and springs 23, while closing bracket 20 is connecteddirectly with piston 6. Together, springs 23 must be at least so strongthat they will only compress when spring 10 has compressed so far thatstop 12 contacts stop plate 7. This can be ensured in a simple mannerthrough the selection of suitable pre-tensions. Closing bracket 20 iscross-shaped, so that it only contacts the center areas of slides 14from below.

Base plate 11 is supported on rods 24. Of course, it is also quitepossible to reverse the direction of travel, and to design centeringbasket 4 and closing bracket 20 stationary with base plate 11 and theother components of this assembly being advanceable.

As can be seen from FIGS. 2a and 217, there are four slides 14, whichare associated to the side walls of tray 1. The slides are divided intotwo independent sections 25 and 26, with section 25 associated to thestraight area of the edges of tray 1 and each section '26 associatedtoahalf corner areaonlysection 25 isimovably retained against rod-likeattachments 18, in accordance with the representation according toFlGS.1a and 1b, while section 26 is fixedly connected with rod- As can beseen from FIG. 2b in particular, sections 26 of the neighbouring slides14 contact one another when the apparatus is. closed. They leavesufficient clearance to the corner of tray 1 for extensions, 5 of,

centering basket 4 to be able to move right to the edge of tray 1 in thecorner areas. As a result, the corner areas are not sealed asintensively as the straightiareas. In actual practice, this has notproven to be a disadvantage, but an advantage, since sufficientsealingis provided in the corner areas by the compression of the lid foilthere, the so-called pleating. In addition,pull tabs. 6

can also be left on lid foil 2 in the corner areasythis permitsadvantageous opening of the trays by pulling these.

pull tabs downward.

Obviously, many modifications and variations of the present inventionare possible in the light of the above teachings. It should therefore beunderstood that within the scope of the appended claims, the inventionmay be practiced otherwise than as specifically described.-

Having .thus fully disclosed my invention, what I.

claim is: g 1. An apparatus for bending the edge of a foil of aluminiumor a similar material around an outwardly projecting edge of a tray, thetray being provided 'with straight edge portions and corner portionsconnecting the straight edge portions, the apparatus comprising; a baseplate means, a centering basket means for receiv-,--

ing and holding the tray with the foil disposed there} over, a stopplate means disposed aboveand spaced from said centering basket means,meansfor selectively displacing said centering basket means into eng gment with said stop plate means, means for mounting".

said stop plate means to permit limited displacement means in the firstdirection being effectedby the limited displacement of said stop platemeans by saidcentering basket means, and a closing bracket means movable with said centering basket means forcontacting said slide means toeffect movement of said slide means I I in the. second directionafter'said centering basketm means contacts said stop plate means.

2. The apparatusaccording to claim 1, in which said: means for mountingsaid slide means includes'lever means disposed at respective lateraledges of said stop plate means, said lever means extending between saidbase plate means and a respective lateral edge ofsaid stop plate means,and at least a pair of spaced shaft means for pivotally .mounting'therespective ends of said lever means, one of said pair of spaced shaftmeans being mounted at said stop plate member and the other a I of saidpair of shaft means being mounted at said base. f

plate means, each of said shaft means extending parallel to the edges ofthetray.

3. The apparatus according to claim 2, in which spring means areprovided for normally urging said stop plate means toward the centeringbasket means, and attachment means located laterally of said stop platemeans for attaching said slide means to said lever means.

4. The apparatus according to claim 3, in which said slide meansincludes a slide member, said attachment means includes a rod membermounted on said lever means, a stop shoulder provided at one end of saidrod member, and spring means for normally urging said slide membertoward said stop shoulder.

5. The apparatus according to claim 1, in which each of said slide meansincludes a first member extending substantially parallel to the straightedge portion of the tray and a second member contoured to a portion ofthe corner portions of the tray, said first member of each of said slidemeans being mounted to effect the successive movement in the first andsecond directions and said second member being fixedly mounted withrespect to said first member.

6. The apparatus according to claim 5, in which said second members ofsaid slide means are set back relative to said first members to permitadjacent second members of adjacent slide means to contact each otherafter said first members effect the successive movements in the firstand second directions.

7. The apparatus according to claim 1, in which said slide meansincludes plates, and stem means for engaging behind an annular bead ofthe edge of the tray to seal the foil thereto.

8. The apparatus according to claim 1, in which the centering basketmeans is provided with corners, said corners have extensions extendingto the edge of the tray.

9. The apparatus according to claim 8, in which spring means forsupporting said centering basket means are provided between saidcentering basket means and said closing bracket means, saidlastmentioned spring means being stronger than the spring means fornormally biasing said stop plate means toward said centering basketmeans.

10. The apparatus according to claim 8, in which a recess correspondingto the size of a lid to be created by the foil is provided in said stopplate means.

11. An apparatus for bending the edge of a foil of aluminium or asimilar material around a surrounding edge of a tray, the foil beingprovided with edges extending beyond the edge of the tray, the apparatuscomprising: a carrier plate means for carrying the tray, a pre-bendingmeans disposed above said carrier plate means for bending portions ofthe foil which extend beyond the edges of the tray, means forselectively raising and lowering said carrier plate means, said carrierplate means in said raised position engaging said pre-bending means topermit said pre-bending means to bend the foil extending beyond theedgcsof the tray toward said carrier plate means, sealing means operativelyconnected with said carrier plate means and said prebending means forpressing the portions of the foil bent toward said carrier plate meansaround the edge of the tray, means for mounting said sealing means topermit successive movement of the same in a first direction toward thetray and, a second direction substantially perpendicular to the edge ofthe tray, and a closing bracket means movable with said carrier platemeans for contacting said sealing means and pushing said sealing meansin the second direction when said carrier plate means and saidpre-bending means are in engagement. l =l

1. An apparatus for bending the edge of a foil of aluminium or a similarmaterial around an outwardly projecting edge of a tray, the tray beingprovided with straight edge portions and corner portions connecting thestraight edge portions, the apparatus comprising: a base plate means, acentering basket means for receiving and holding the tray with the foildisposed thereover, a stop plate means disposed above and spaced fromsaid centering basket means, means for selectively displacing saidcentering basket means into engagement with said stop plate means, meansfor mounting said stop plate means to permit limited displacementthereof by said centering basket means, a plurality of slide means forcontacting and bending the respective edges of the foil from the outsidethereof, pivot means connected with said base plate means and said stopplate means for pivotally mounting said slide means to permit at least aportion of said slide means to effect successive movement in a firstdirection toward the tray and in a second direction substantiallyperpendicular to the edge of the tray, the movement of said slide meansin the first direction being effected by the limited displacement ofsaid stop plate means by said centering basket means, and a closingbracket means movable with said centering basket means for contactingsaid slide means to effect movement of said slide means in the seconddirection after said centering basket means contacts said stop platemeans.
 2. The apparatus according to claim 1, in which said means formounting said slide means includes lever means disposed at respectivelateral edges of said stop plate means, said lever means extendingbetween said base plate means and a respective lateral edge of said stopplate means, and at least a pair of spaced shaft means for pivotallymounting the respective ends of said lever means, one of said pair ofspaced shaft means being mounted at said stop plate member and the otherof said pair of shaft means being mounted at said base plate means, eachof said shaft means extending parallel to the edges of the tray.
 3. Theapparatus according to claim 2, in which spring means are provided fornormally urging said stop plate means toward the centering basket means,and attachment means located laterally of said stop plate means forattaching said slide means to said lever means.
 4. The apparatusaccording to claim 3, in which said slide means includes a slide member,said attachment means includes a rod member mounted on said lever means,a stop shoulder provided at one end of said rod member, and spring meansfor normally urging said slide member toward said stop shoulder.
 5. Theapparatus according to claim 1, in which each of said slide meansincludes a first member extending substantially parallel to the straightedge portion of the tray and a second member contoured to a portion ofthe corner portions of the tray, said first member of each of said slidemeans being mounted to effect the successive movement in the first andsecond directions and said second member being fixedly mounted withrespect to said first member.
 6. The apparatus according to claim 5, inwhich said second members of said slide means are set back relative tosaid first members to permit adjacent second members of adjacent slidemeans to contact each other after said first members effect thesuccessive movements in the first and second directions.
 7. Theapparatus according to claim 1, in which said slide means includesplates, and stem means for engaging behind an annular bead of the edgeof the tray to seal the foil thereto.
 8. The apparatus according toclaim 1, in which the centering basket means is provided with corners,said corners have extensions extending to the edge of the tray.
 9. Theapparatus according to claim 8, in which spring means for supportingsaid centering basket means are provided between said centering basketmeans and said closing bracket means, said last-mentioned spring meansbeing stronger than the spring means for normally biasing said stopplate means toward said centering basket means.
 10. The apparatusaccording to claim 8, in which a recess corresponding to the size of alid to be created by the foil is provided in said stop plate means. 11.An apparatus for bending the edge of a foil of aluminium or a similarmaterial around a surrounding edge of a tray, the foil being providedwith edges extending beyond the edge of the tray, the apparatuscomprising: a carrier plate means for carrying the tray, a pre-bendingmeans disposed above said carrier plate means for bending portions ofthe foil which extend beyond the edges of the tray, means forselectively raising and lowering said carrier plate means, said carrierplate means in said raised position engaging said pre-bending means topermit said pre-bending means to bend the foil extending beyond theedges of the tray toward said carrier plate means, sealing meansoperatively connected with said carrier plate means and said pre-bendingmeans for pressing the portions of the foil bent toward said carrierplate means around the edge of the tray, means for mounting said sealingmeans to permit successive movement of the same in a first directiontoward the tray and, a second direction substantially perpendicular tothe edge of the tray, and a closing bracket means movable with saidcarrier plate means for contacting said sealing means and pushing saidsealing means in the second direction when said carrier plate means andsaid pre-bending means are in engagement.